JP-A-7-97334 discloses a sustained release formulation consisting of a physiologically active peptide or its salt and a biodegradable polymer having a terminal free carboxyl group as well as a method for producing the same.
Each of GB2209937, GB2234169, GB2234896, GB2257909 and EP626170A2 discloses a composition comprising as a base a biodegradable polymer containing a water-insoluble salt such as a pamoate of a peptide or a protein prepared separately as well as a method for producing the same.
WO95/15767 discloses an embonate (pamoate) of cetrorelix (LH-RH antagonist) and a method for producing the same, and describes that this pamoate, even when enclosed in a biodegradable polymer, exhibits the peptide-releasing performance equivalent to the pamoate which exists independently.